A period investigation of the overcontact binary system V417 Aquilae

Abstract

A detailed orbital period investigation of the short-period () W UMa type star, V417 Aql, is presented based on the analysis of its O–C data. It is shown that the period change of the binary system is continuous. A periodic variation, with a period of 42.4 years and an amplitude of , is found superimposed on a long-term period decrease ( days/year). The period oscillation can be explained either by the light-time effect via the presence of an unseen third body or by magnetic activity cycles of the components. V417 Aql is a W-type overcontact binary system with a low mass ratio of . The long-term period variation is in agreement with the conclusion of Qian ([CITE]b) that a low-mass ratio W-type system usually shows a secular period decrease. This suggests that V417 Aql is on the AML-controlled stage of the evolutionary scheme proposed by Qian ([CITE]b). Meanwhile, the light-curve paradox encountered by TRO theory is discussed.